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Daniel M Sciubba,
E Clif Burdette,
Jennifer J Cheng,
William A Pennant,
Joseph C Noggle,
Rory J Petteys,
Christopher Alix,
Chris J Diederich,
Gabor Fichtinger,
Ziya L Gokaslan, Kieran P Murphy
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ABSTRACT: Radiofrequency ablation (RFA) has proven to be effective for treatment of malignant and benign tumors in numerous anatomical sites outside the spine. The major challenge of using RFA for spinal tumors is difficulty protecting the spinal cord and nerves from damage. However, conforming ultrasound energy to match the exact anatomy of the tumor may provide successful ablation in such sensitive locations. In a rabbit model of vertebral body tumor, the authors have successfully ablated tumors using an acoustic ablator placed percutaneously via computed tomography fluoroscopic (CTF) guidance.
Using CTF guidance, 12 adult male New Zealand White rabbits were injected with VX2 carcinoma cells in the lowest lumbar vertebral body. At 21 days, a bone biopsy needle was placed into the geographical center of the lesion, down which an acoustic ablator was inserted. Three multisensor thermocouple arrays were placed around the lesion to provide measurement of tissue temperature during ablation, at thermal doses ranging from 100 to 1,000,000 TEM (thermal equivalent minutes at 43°C), and tumor volumes were given a tumoricidal dose of acoustic energy. Animals were monitored for 24 hours and then sacrificed. Pathological specimens were obtained to determine the extent of tumor death and surrounding tissue damage. Measured temperature distributions were used to reconstruct volumetric doses of energy delivered to tumor tissue, and such data were correlated with pathological findings.
All rabbits were successfully implanted with VX2 cells, leading to a grossly apparent spinal and paraspinal tissue mass. The CTF guidance provided accurate placement of the acoustic ablator in all tumors, as corroborated through gross and microscopic histology. Significant tumor death was noted in all specimens without collateral damage to nearby nerve tissue. Tissue destruction just beyond the margin of the tumor was noted in some but not all specimens. No neurological deficits occurred in response to ablation. Reconstruction of measured temperature data allowed accurate assessment of volumetric dose delivered to tissues.
Using a rabbit intravertebral tumor model, the authors have successfully delivered tumoricidal doses of acoustic energy via a therapeutic ultrasound ablation probe placed percutaneously with CTF guidance. The authors have thus established the first technical and preclinical feasibility study of controlled ultrasound ablation of spinal tumors in vivo.
Journal of neurosurgery. Spine 12/2010; 13(6):773-9. · 1.61 Impact Factor
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ABSTRACT: Acute proximal aortic dissection may be complicated by stroke due to malperfusion of the arch vessels. We report a novel case of successful endovascular treatment of acute cerebral malperfusion due to a dissection involving the aortic arch.
A 66 year old man was transferred from another hospital with an acute type I aortic dissection and underwent emergent repair of the aortic valve and ascending aorta with a composite graft. Left hemiplegia and altered cognitive function were noted on postoperative day 1. A carotid duplex scan showed partial thrombosis of the right carotid artery with very slow flow and reversal of flow in the right vertebral artery. A head CT was normal, while a head MRI and MR angiogram showed intraluminal defects in the inominate and right carotid arteries and perfusion abnormality of the entire right middle cerebral artery territory, but only small infarcts of watershed areas. The patient underwent stenting of the right carotid and inominate arteries through the right carotid artery with complete resolution of a large pressure gradient that was noted prior to stenting. The patient's left hemiplegia and cognitive impairment subsequently resolved during his inpatient hospitalization. On follow up five months later, he had a normal neurologic exam and MRI showed old watershed infarcts but no perfusion abnormality. On most recent follow-up 2.5 years after treatment, he remains well and a CT angiogram shows that his stented vessels remain patent.
Endovascular techniques may be safely applied to correct cerebral malperfusion that results from type I aortic dissection.
Journal of Vascular Surgery 12/2006; 44(5):1091-6. · 3.21 Impact Factor
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ABSTRACT: Fractures of the proximal femur are common sequelae of osteoporosis, and are responsible for significant morbidity and mortality in elderly patients worldwide. Plain film radiographic assessment methods to assess for fracture risk may be of particular value.
The authors present the results of biomechanical testing, radiographic imaging, and histologic exam of 20 embalmed human bone specimens, with implications for clinical correlation of radiologic findings. Authors assessed bone architecture using the Singh Index, using a blinded 3-rater system to reduce bias and measure intra-observer reliability. After loading to failure with ultimate tensile strength (UTS), bone specimens were assessed by fracture location type and by trabecular bone volume (TBV).
Singh scoring was performed with Inter-Class Correlation of 0.80 (F=0.24, by ICC Portney Model 2). A statistically-significant difference among the UTS distributions was noted for UTS by Fracture Site (F=4.49, p=0.026, by ANOVA). No significant association of Singh Index with TBV, or TBV with UTS, was observed, although a trend toward greater UTS with higher Singh grade was observed.
The authors propose that the Singh Index is a valuable and reliable indicator which may reflect structural integrity in trabecular bone. Fracture site along the femur is associated with tensile strength. The authors, in the light of these findings, address the promise and potential impact of prophylactic hip augmentation in populations at risk for femoral neck pathology.
Skeletal Radiology 04/2006; 35(4):202-11. · 1.54 Impact Factor
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ABSTRACT: Adhesion and migration of leukocytes into the periadventitial space play a role in the pathophysiology of vasospasm after subarachnoid hemorrhage (SAH). Intercellular adhesion molecule-1 is a determinant cell adhesion molecule involved in this process. Ibuprofen has been shown to inhibit intercellular adhesion molecule-1 upregulation and prevent vasospasm in animal models of SAH. In this study, we report the toxicity and efficacy of locally delivered ibuprofen incorporated into controlled-release polymers to prevent vasospasm in a monkey model of SAH.
Ibuprofen was incorporated into ethylene-vinyl acetate (EVAc) polymers at 45% loading (wt:wt). For the toxicity study, cynomolgus monkeys (n = 5) underwent surgical implantation of either blank/EVAc polymers (n = 3) or 45% ibuprofen/EVAc polymers (n = 2) in the subarachnoid space, were followed up for 13 weeks, and were killed for histopathological analysis. For the efficacy study, cynomolgus monkeys (n = 14) underwent cerebral angiography 7 days before and 7 days after surgery and SAH and were randomized to receive either a 45% ibuprofen/EVAc polymer (n = 7; mean dose of ibuprofen, 6 mg/kg) or blank EVAc polymers (n = 7) in the subarachnoid space. Angiographic vasospasm was determined by digital image analysis. Student's t test was used for analysis.
Animals implanted with ibuprofen polymers showed no signs of local or systemic toxicity. Animals treated with ibuprofen polymers had 91 +/- 9% lumen patency of the middle cerebral artery, compared with 53 +/- 11% of animals treated with blank/EVAc polymers (P < 0.001).
Ibuprofen polymers are safe and prevent angiographic vasospasm after SAH in the monkey model. These findings support the role of cell adhesion molecules and inflammation in the pathophysiology of vasospasm.
Neurosurgery 07/2005; 57(1 Suppl):184-90; discussion 184-90. · 2.79 Impact Factor
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ABSTRACT: Intraventricular hemorrhage (IVH) uncommonly occurs in an otherwise healthy term neonate. We report a case of IVH in a term infant that was the result of an angiographically demonstrated arteriovenous malformation (AVM) despite the infant having a cranial ultrasonogram and magnetic resonance angiogram, which did not demonstrate the AVM.
Journal of Pediatrics 12/2002; 141(5):710-1. · 4.11 Impact Factor
